The present invention relates to a height adjustment system for an air suspension of a vehicle having an oscillation damper and comprising air springs, solenoid valve means for controlling air flow through the air springs, a distance sensor for sensing the distance between the vehicle body and a respective axle, and control means for controlling operation of the valve means in accordance with the distance. Such a system is known from EP-A-0091017 wherein compressed air is admitted to the air spring when a distance sensor senses that the height of the vehicle body is below a lower threshold, and air is released from the air spring when the distance sensor senses that the body height is above an upper threshold. As a result of frictional forces in the damper, the adjustment travel extends beyond that at closing of the solenoid valve arrangement. An attempt to compensate for this overshoot is made by appropriate choice of the upper and lower thresholds. However, this does not take into account the fact that the amount of overshoot depends also on the velocity of vertical movement of the vehicle body relative to the axle at the instant of closing of the valve arrangement and possibly other factors.